heath



Feb. 18, 1936. F. A. HEATH Re. 19,860

OIL BURNING FURNACE Original Filed Feb. 10, 1928 2 Sheets-Sheet l BY JATTORNEY Feb. 18, 1936. H T Re. 19,860

OIL- BURNING FURNACE 4 Original Filed Feb. 10. 1928 2 Sheets-Sheet 2'leissued Feb. 18, 1936 UNITED STATES PATENT OFFICE.

on. BURNING FURNACE Forrest A. Heath, Upper Montclair, N. J.

Original No. 1,886,675, datedNovember 8, 1932, Serial No. 253,271,February 10, 1928. I tenewed March 12, 1930. Application for reissueOctober 25, 1934, Serial No. 750,024

35 Claims.

I My present invention is related to that set forth in my companionapplication Serial No. 253,270, flied February 10, 1928 now Patent No.1,979,465, granted November 6, 1934. It concerns oil burning apparatusof the class in which metered, and more or less mixed oil and air aresprayed, preferably centrifugally above a refractory hearth that closesin the lower end of a fire box and more specifically to apparatus havingthe oil projecting means and the hearth organized and operating in suchcombination that in normal full operation as well as at starting, theflame line or region where active combustion is precipitated islocalized adjacent the periphery of the hearth which thus functions asthe burner. My present invention also contemplates the use in such acombination of certain features of my prior invention, disclosed andclaimed in said companion application, including some of the features ofthe hearth, which are herein claimed only in combination with certainmodifications and additions whereby my present hearth is even betteradapted to improve the certainty and speed of ignition; to lessen thedanger of having the ignited oil flame put out by being smothered inexcess gas evolved at starting; and,

in normal full operation, to more certainly 1o calize at the periphery,the zone where active l combustion is precipitated.

One feature of said application adapted to my present invention concernshaving the periphery of the hearth formed with vertical impingementsurfaces of fire brick orthe like, adapted to aflord catalytic surfacestop-recipitate combustion at the periphery after the refractory materialgets highly heated in normal running. One or more such impingementsurfaces extend upward to or above the highest horizontal level to whichthe oil can be projected by the projecting apparatus, so that most ofthe unatomized drops of the projected oil impinge thereon. In lmy priorapplication, this'impact and ignition wall j is closely adjacent thewall ofthe fire box and operates like a burner from which the flamerises in contact with said fire box wall. My present inventioncontemplates rearrangements and additions whereby this somewhatprimitive burner is evolved into a more definite type of burner adaptedto discharge flame more directly on the blast of flame and combustiblemixture into conwall to be heated. One feautre is spacing this tact withthe wall of the furnace. In practice, the combustible draft from therotary projector is deflected upward by the impact and ignition wall sothat it shows a tendency to curl back away from the wall toward thecenter portions of the fire box, but it may be readily understood thatwhen such upward draft blast passes the upper margin of a wall having arear space, the

blast tends to draw a vacuum in said space, there- 'faces become whitehot, promoting perfect, combustion, even though the flame and draftthere from pass immediately into contact. with the relatively cold wallsof the water leg of the boiler. While the vacuum and eddy producingeffect of the space behind the impact wall is inherent, my

present invention includes the further feature of having the spacedapart cooperating refractory wall, forwardly sloping and provided withrearwardly directed reticulations through which the flame may bedefinitely directed upon the wall to be heated. The space adjacentthefront of this cooperating refractory wall, in reverberatory relationto the rear surface of the impact wall becomes a hot gas generatingregion, and if the rear wall is forwardly sloping, the reticulationswill cause the rear face to function like a multiple gas jet burner, thejets whereof are directed against thewater leg to be heated. In thelatter particular it is analogous to a Welsbach mantie whenover-supplied with gas and air mixture. In the form shown, the rear wallof this reverberatory space extends forward far enough to overhang thevertical impact surface, tending to positively deflect the flame and gasmixture rearwardly behind the impact wall, in addition to the abovedescribed induction or vacuum effect whereby the flame and gasesnaturally tend to curl and eddy behind the wall.

- As in my companion case, I may use one or more collecting gutters orgrooves adjacent the base of the impingement surface, said gutter orgutters being of cross section sufficient to hold all of the unignitedoil that can collect during the starting period. This peripheral guttermay be a pronounced groove, of depth dependent on the area of theimpingement surface draining thereto, so that the exposed top surface'of the oil collected therein is of relatively 'small area.

Another feature cooperating well with the collecting gutter, but whichmay be suflicient in itself, is to provide for an out drainage of thehearth dow/nward from the oil projector to the periphery. "Preferably,the upper surface of, the hearth is sloped so that it will be close tobut out of range of the trajectory of the lowest part of the projectedoil. Where such down'slope hearth is used, it forms a collecting annulusor gutter where it meets the base of the vertical-or upwardly extendingsurface of a peripheral impact wall. In the present case, the down.slopehearth drains into such acollecting annulus adjacent a very lowvertical surface, the main impact wall and its gutter being further ontoward the periphery. It is just as welLor even better tohave thedrainage from the hearth into a gutter. In either case, the down slopeplus the gutter mutually cooperate to produce the best results, the downslopetending to keep the hearth free from impingement of unignited oiland facilitating outward drainage of any that does impinge, while thegutter tends to minimize the exposed surface of the oil collectedtherein.

' As explained in my companion application, this makes it possible tostart with the oil projector projecting only the amount of oil necessaryfor normal and yet accumulate at the periphery where it is to beignited, an ample supply -of oil, in evenless time than would bepossible by an over-supply of oil projected upon the usual up-slope orhorizontal hearth which does not have any peripheral gutter. Thus theoil is conhearth and burner, fire boa wa r'l a; I Figure la is'anenlargedsectional detail showinggoreclearlyandfullythefananddraftarrangements of the burner head Figure 2 is a plan view of the burner;Figures 3 and 4 are enlarged elevations of the refractory burnerstructural elements; and

Flgure5isa'sectionon the line 5-,Figure4. '5Thefurnaeetobeheatedisshowninl igure l as including a wall creasing l,closing in a space and supports the furnace which may be of any'desiredconstruction, the essential parts shown in {affording an inter-space 4for An annular ledge I supports a hearth pan 8 'stiflened by radial Thissupports .a refractory hearth I which projects an air and oil projectorconventionally indicated at A.

- hearth is formed at its periphery with th vertical fuel impingementandignition wall 8 having at the base thereof an oilcollectinggutter,'in this case a groove I the depth of which is aboutequal to, its width,

' the present case, th' hearth elements are set to that there a aslightly P jecting vertical Figure lis'a vertical sectional view of the'beingthewalllclosingintheflrebox.

to be heated or boiled, as the surface ill just inside of and parallelwith the gutter 9 which is at thefoot of the main impingement' andignition wall 8. When so set, as

and when used in combination with the outwardly down sloping hearth, anydrainage from the hearth will beto the annular collecting space Illa atthe foot of this wall. It will be understood,

however, that in many cases the rim of the gut-.

ter 9 will 'be set flush with the uppersurface of the hearth.

- it sometimes is, on hearths of small diameter,

Ignition torches II, II are set in position to F discharge ignitionflame across the gutter 9 and against the ignition wall 8, and if thereis a smaller wall III- as shown, part of the ila'me will play upon thiswall also.

, Various examples of oil and air projectors suitable for my purpose arenow well known. One is the oil projector invented by Homer A. Tiffany,

1' r which application for letters patent has been or is about to bemade, and another is set forth in my application Serial No. 47,709,filed August 3rd, 1925, which has resulted in Patent No. 1,707,474,issued April 2, 1929. The former is the one conventionally indicatedvherein. I

The oil is centrifugall'y discharged in an ex tremely the spray or vaporthrough nozzles l2,

supplied through a head ll mounted on vertical creating a powerful draftbelow the trajectory of the oil as suggested by the arrow 2. as shown inFigures 1 and la, there are ten or a dozen fan blades I! carried byunder face of the head i3. These constitute a large volume fan tendingto create a vacuum in the interior space a. The four nozzles l2constitute anothersfan creating suction at e, and through annularpassage d this suction takes eflect in the same space that the. fan Itdraws from The air inlet to this space a is through aslot bcommunicating with the ash pit. cross section of this slot may beadjustab decreased orincreased by vertical slide In operation, 011 issupplied to the trough e through a suitable interior nomle notshown.Centrifugal force causes a film of this oil from trough e to creep upthe walls and ultimately to be w n 08 as a fine spray proiected from therear 1 ps of the four nozzles If. Centrifugal force also causes arelatively small volume of air .to be, projected through these nozzlesI! while amuch larger volume of air is being projected by the fan bladesIS. The nomles project sub- .stantially above the plane of the top plateit of the rotor; Consequently, said plate, together with the upwardlyprojecting surfacesof the nozzle, constitute in effect a third fanwhereby hot products of combustion are projected in the same horizontalplane with the spray. The projected products of combustion and the airenveloping the much less than, that of the annulus through which bladesl5 discharge.

fractory impact surfaces are at high heat, the

combustion at the periphery is substantially perfect. The oil and airsupplies to the burner, as also the means for metering the same, form nopart of my present invention and are not shown. Similarly, the means forcontrolling supply of gas to the ignition torches ll may be of any knownor usual construction and are not shown. The important features are thatthe ignition torch nozzles H are located inside the circumference of thecollecting groove and the flame therefrom impinges along the ignitionwall, preferably in the same direction that.the.rotary head tends torotate the body of air or gas within the fire box.

I have discovered by many experiments that an outward down slope for thehearth of approximately one-half inch to the foot is sufficient *tion.

to keep the upper surface below the trajectory of the oil, even when thediameter of the fire box is a maximum. As a specific illustration ofpreferred construction, I may note that an eightinch rotary head l2, l3,may be utilized for fire boxes of widely varying diameter simply byvarying the metering of the oil and gas, a uniform running speed of,say, 1,700 revolutions per minute being maintained for all sizes offurnaces and all degrees of heat. Where such a head is used in a firebox having a hearth only 24 inches in diameter, the oil only has to bethrown 8 inches. In such a case, a slight down slope to the hearth isdesirable, although the distance is so short that the oil will certainlyclear the hearth, regardless of whether the upper surface of the hearthis horizontal or is slightly sloping in either direc- For such smalldiameters, the collecting groove alone may be sufficient without theslope. With greater diameters, the outward down slrpe is progressivelyof greater importance, but for all sizes of hearth up to say, 78 inchesin diameter. the standard outward down slope of one-half inch to thefoot is sufficient.

So far as concerns the main impact surface or surfaces and the gutter,it will be recognized that they correspond to similar parts in mycompanion application, but as above described their functioning afterthey get hot, in full normal operation, is combined with and modified byadditional parts and features of construction whereby the simple walland groove burner becomes more a gasifying and mixing region furnishinggas to and through other elements which have a more characteristicburner function.

structure, is built up of relatively short molded sections of fire brickor other refractory catalytic material. As the cross section issubstantially uniform except at one point to be mentioned hereafter,these sections may be madeas standard desired diameter or shape offurnace. In the form illustrated in Figure 2, the fire box is squareThus the composite draft pro- L molded units which may be assembled toflt any I and similar units in varying lengths are sawed or otherwiseformed to fit as at a, b', c, d, etc. As shown on Sheet 2 of thedrawings, the units preferably comprise a base member 9a., affording thegutter 9 and affording also a support for an integral upright elementto. In the rear of this is a relatively small space or cavity arrangedso as to be vacuumized by the draft deflected upward by impinging on thefront wall of said element, whereby in normal operation the flame andcombustible mixture tends to curl and eddy backward into said space, asabove described. In the form shown, the rear face 8b slopes downward ata relatively steep angle to a flat surface 80 and has integral therewithupstanding ribs 8d, affording a support surface 8e, preferably parallelwith 8b, and a ledge or stop, 81'.

In this form, the cooperating reverberatory surface is afforded byutilizing the support surface as a spacer and support for asuper-structure including a refractory burner slab l8, sloping upwardand projecting over the wall 8 a considerable distance so that its freeedge Ila is vertically be- .yond the gutter 9. This slab has burnerpassagesv or reticulations I817.

The relative areas of the surfaces, as well as the area and angle of theoverhang l8a admits of considerable variation, but the object is firstto intercept all of the unatomized drops upon the refractory facespresented toward the center of the hearth and while most of it ispreferably received upon the surface 8 and drains directly into thegutter 8, it is evident that scattering drops may be intercepted by theburner plate II and if the hearth projects as at Ill, some drops mayfall on this vertical surface. Drops striking above the surface 8 willnaturally drain or be blown by the air draft rearward to the spacebehind the burner structure. a For this reason, I prefer to have thearea surface 8}, Figure 5, spaced slightly apart from the fire box wall2. Any 011 draining to this pocket will be practically out of the fieldof operations during the starting period, but after the apparatus is infull operation, this oil will be volatilized and burned so that no greatexcess accumulates. In order to provide a path of escape for any suchexcess I arrange a slot-like passage 8x, whereby this space drains downthe surface 811 into the gutter 9 in front of the ignition surface 8.

Another factor controlling the proportions of the parts, particularlythe angle and overhang of the burner plate at Mia. and the height of thesupports Be is to have the horizontally discharged blast from theprojector pocketed and deflected so that it will be discharged partlythrough the burner retioulations lb, and partly downward along thesurface 8b, directly to the fire box wall 2.

These things will be further explained from theoperation of theapparatus which may be described as follows:

The usual controls are employed whereby power is supplied to rotatethehead It to deliver a predetermined metered supply of oil along thelines 1:, u and air or air and hot gas, as indicated by the arrow 2, theoil projected against ignition wall 8 collecting in groove 9. Some of itmay be projected under or through the slab II, but this drainsrearwardly as described above. The maximum exposed surface of oil istherefore practically limitedt'o the area of the exposed burner surfacesplus the upper surface area of the oil in groove 9. All of the oil beingconcentrated in the ignition region, the ignitiomtorches quickly,

ignite the on around the entire periphery,but anyincreasedoilsurfacethatsuchignltion brings 'into play, is above and beyond the'aone oftheignition airface and gutter, there being little, if any, oil on theupper surfaces of the hearth. consequently the igniting operation isquick and uniformly progressive until the entire periphery flames. Any011 on the overhang or undersurface of burner plate It is in the bestpossible position to intercept and be vaporized by the growing blazefrom below.

It will be noted that during the ignition period,

the combustible blast mixture is deflected through the burner andcleared of excess oil drops carried thereby, thus tending to correct thenatural overrichness' of the mixture at this stage when so much oil is'being evaporated from the wet surfaces. The burner plate It andparticularly theoverhang portion thereof, being thin, quickly becomeincandescent, as also the thin'upper tips and edges of the projectingsupports (1.; Later on, all of the surfaces'become hot enough so thatinnormal running all oil droplets are vaporized immediately upon impactwith the burner surfaces.

Another very important function of the burner plate is that of ahomogenizing mixer. The blast from the projector nozzles is more or lessflnelyy/ally dlscha subdivided or atomized spray. is.deliveredbelow-thespray by the fan and naturallytends to cross the path of *the spray andforms with it a combustible blast that carries on its upper surface an'admixture of burned out gas rich in carbon dioxide. This three-foldmixture projected against the burner is thoroughly bailed andhomogenized as part of it is through the reticuiaticns of the burnerplate part is deflected downward-and rearward under the plate. Theadvantage of such a homogeneous mixture is well known and the specialadvantage of the carbon dioxide diluent is also well known as conduciveto a voluminous flame, of less intensity but much greater heating eifectas concerns the fire wall 2.- In normal full operation, my presentinvention makes it possible to u out down the air to just the amountneeded for complete combustion with the result that the flame may bealmost invisible, like the blue part of the flame froma well regulatedBunsen burner.

. An important feature is that'this flame is directed through the burnerplate and downward under the plate directly 'into contact with the wall2, and starts its upward licking p we; undisturbed by the blast from thefan.

The. ignition torch may and frequently does ceasetobeflamingwhen theoilisbeingrapidly vaporized and burned in close proximity thereto.

There is no disadvantage because the torch gas isburned along with theoil vapor so long as norrnal operation continues. The remarkable pointis that when the oil projector is turned off and the oil flame diesdown, it naturally shrinks down behind the ignition wall to the'surplusofl there collected and then follows oilthrough the slot 0: intothegroove, thus relighting the ignition torch before itself becomingextinguished. Or if the ignition torch is intermittently operated by apilot light proiecting upward in the groove 1, as in my canpanionapplication, it will be the pilot-that is relighted in this-way.

while I have shown the. flre box as-being it is to be understoodvthat inpractice they are often oblong or circular. In such cases the peripheralburner preferably follows the fire boximpact surfaces. I

P the projected on and deflect the draft upward, an:

wall inthe relation indicated incroa section in Figure 1, although it isdesirable to have it cut across the extreme angles of the corners asshown. a h

I claim: lsAp'paratus of the class described, including a furnace,'ahearth closing in the bottom thereof, and a centrifugal projectorradially discharging a composite draft of air adjacent the upper surfaceof the hearth and oil above the air, said projector and hearth beingdesigned and operating to maintain combustion in a peripheral zone ofimpact and disturbance of the projected composite draft; and, extendingalong said peripheral zone. a homogenizing burner of refractory materialadapted to intercept the path of the projected oil. an oil collectinggutter in drainagerelation to said homogenizing burner, a rear oil rain:a composite draft of air adjacent the per surface of the hearth and onabove thfljfi-ll', and a homogenizing gasifying burner of.

refractory material adjacent the upright furnace walls all designed andoperating to maintain the bottom thereof, a centrifugal projectorradicombustion in a peripheral zone of impact and disturbance of theprojected composite draft; said burner being formed with wall elementshaving upwardly nding, inwardly presented to intercept the path of I oilcollecting gutter in drainage-relation to said impact -surfaces,-saidburner having also transverse es and an overhanging deflector eledeflectthe upward draft outinent arranged ward against sai furnace walls.

3. Apparatus'of the class described, including I a furnace having anupright wall, a hearth closing in the bottom thereof, a, centrifugalprojector radially 4 a composite draft of air adjacent the upper surfaceof the hearth and oil above the air, and a homogenizing gas'ifyingburner of refractory material adjacent said upright wall, all designedand operating to maintain combustion in a peripheral zone of impact anddisturbance of the projected composite draft; saidburner being formedwith. wall elements having-upwardly extending inwardly presentdd'im'pactsurfaces adapted to intercept the path of the projected oil and deflectthe draft upward, a rear oil collecting gutter behind said burner, and adrainage passage draining from said rear gutter to the front of saidwall.

1 '4. Apparatus hr the dissent-scribed, including" a furnace havingupright walls, a hearth closing in the bottom thereof, a centrifugalprojector radially discharging a composite draftof 'air adjacent theupper surface of the hearth and oil above the air, and a homogenizinggasifying" burner of refractory material adjacent the upi right furnacewalls, all designed and operating to maintain combustion in a peripheralzone of im-:

pact and disturbance of the projected composite;

draft; said burner being formed with wall elements having upwardlyextending, inwardly presented impact surfaces adapted to intercept thepath of the projected oil and deflect the draft in the bottom thereof, acentrifugal projector radially discharging a composite draft of airadjacent the upper surface of the hearth and oil above the air, and ahomogenizing gasifying burner of refractory material adjacent saidupright wall, all designed and operating to maintain combustion in aperipheral zone of impact and disturbance of the projected compositedraft; said burner being formed with wall elements having upwardlyextending, inwardly presented impact surfaces adapted to intercept thepath of the projected oil and deflect the draft upward, said burnerhaving also a burner plate having reticulations through which the draftflows.

6. Apparatus of the class described, including a flre box, a refractoryhearth structure including a hearth closing in the bottom thereof and arotary head comprising a centrifugal oil sprayer and an air projectordischarging horizontally below the oil sprayer, above the hearth, saidhearth having a substantially unobstructed upper surface lying below thelevel of normal projection of the oil spray, designed and operating toinitiate combustion adjacent the periphery of the hearth, said hearthstructure having adjacent the periphery an upwardly extending refractoryignition wall, adepression at the base of said wall for collecting oilsplashing or draining downward from the front face thereof and drainage'means formed in the wall whereby oil projected beyond the impact facethereof may drain to said front oil collecting space. v

7. Apparatus of the class described, including a furnace having uprightwalls, a hearth closing in'the bottom thereof, a centrifugal projectorradially discharging air and oil over' the upper surface of the hearthand creating a draft that approaches said upright walls, and ahomogenizing gasifying burner adjacent the upright furnace walls, alldesigned and operating to maintain combustion in a peripheral zone ofimpact and disturbance of the projected air and oil; said burner beingformed with wall elements having inwardly presented impact surfacesshaped and disposed to. intersect the path of the projected oil anddeflect the draft upward, said burner having also a deflector elementarranged to deilect the draft against said furnace walls.

8. Apparatus of the class described, including a furnace having uprightwalls, a hearth closing in the bottom thereof, a centrifugal projectorradially discharging a composite draft of airadjacent the upper surfaceof the hearth and oil above the air, and a homogenizing gasifying burnerof refractory material adjacent the upright furnace walls, all designedand operating to maintain combustion in a peripheral zone of impact anddisturbance of the projected composite draft; said burner being formedwith wall elements having upwardly extending, inwardly presented impactsurfaces adapted to intercept the path of the projected oil and deflectthe draft upward,

jacent the upper surface of the hearth and oil above the air, and ahomogenizing gasifying burner of refractory material adjacent theupright furnace walls, all designed and operating to maintain combustionin a peripheral zone of impact and disturbance of the projectedcomposite draft; said burner being formed with wall elements havingupwardly extending, inwardly presented impact surfaces adapted tointercept the path of the projected oil and deflect the draft upward,said burner having also an upper overabove the air, and a homogenizinggasifying burnerof refractory/material acfiacent the up right furnacewalls, all designed and operating to maintain combustion in a peripheralzone of impact and disturbance of the projected, composite draft saidburner being formed with wall elements having upwardly extending,inwardly presented impact surfaces adapted to intercept the path of theprojected oil and deflect the draft upward, said burner having also anoutwardly and downwardly sloping burner plate arranged to deflect theupward draft outward against said furnace walls.v

11. Apparatus of the class described, including a furnace having uprightwalls, a hearth closing in the bottomthereof, a centrifugal projectorradially discharging a composite draft of air adjacent the upper surfaceof the hearth and oil above the air, and a homogenizing gasifying burnerof refractory material adjacent the upright furnace walls, all designedand operating to maintain combustion in a peripheral zone of impact anddisturbance of the projected composite draft; said burner being formedwith wall elements having upwardly extending, inwardly presented impactsurfaces adapted to intercept the path of the projected oil anddeflectthe draft upward, said burner having also passages for permittingoutward flow of the draft, and a burner plate supported above saidimpact surfaces by spacing elements to afford transverse passagesarranged to direct the upward draft outward against said furnace walls.

12. Apparatus of the class described, including a fire box, a.refractory hearth structure including a hearth closing in the bottomthereof and a rotary head comprising a centrifugal oil sprayer and anair projector discharging horizontally below the oil sprayer, above thehearth, said hearth having a substantially unobstructed .upper surfacelying below the level of normal projection of the oil spray, alldesigned and operating to maintain combustion adjacent the periphery ofthe hearth, said hearth structure having adjacent the periphery anupwardly extending refractory ignition wall and above said wall a plateelement and supports therefor, adapted to intercept oil projected by theoil sprayer.

13. Apparatus of the class described, including a fire box, a refractoryhearth structure including a hearth closing in the bottom thereof and arotary head comprising a centrifugal oil sprayer and an air projectordischarging horizontally below the oil sprayer, above the hearth, saidhearth having a substantially unobstructed upper surface lying below thelevel of normal projection of tain combustion adjacent the periphery ofthe hearth, said hearth structure adjacent the periphery an upwardlyextending refractory ignition wall and above said wall a plate elementand supports therefor, adapted to intercept oil projected by the oilsprayer, and said wall having itsupper surface draining outward towardthe periphery.

14. Apparatus of the class described; including a flre box havingupright walls, a refractory hearth structure including a hearthclosingin the bottom thereof and a rotary-head comprising a centrifugal oil andair projector discharging above thehearth,:said hearth having asubstantially unobstructed upper surface lying below the level of normalprojection of the discharged oil, said hearth structure having adjacentthe periphery a refractory wall with spaced-apart projections extendingupwardly above said level, said refractory wall being arranged to affordimpact surfaces in the path of said spray and surfaces presentedrearwardly adjacent said upright walls of the fire box.

15. Apparatus of the class described, including a fire box havingupright walls, a refractory.

hearth structure including a hearth closing in the bottom thereof and arotary head comprising a centrifugal oil and air projector dischargingabove the hearth, said hearth'having a substantialLv unobstructed uppersurface lying below the level of normal projection of the dischargedoil, said hearth structure having adjacent the periphery an upwardlyextending refractory impact wall, a rearwardly extending face of whichis adjacent but spaced apart from said the box walls, in combinationwith a member afl'ording supplemental refractory surfaces inreverberatory relation to said rearwardly extend-- ing face of saidimpact wall and affording spaced apart paths for escape of flame andcombustible mixture from the reverberatory space into-contact with saidupright walls of the flre box.

16. Apparatus of the class described, including a flre box havingupright walls, a refractory hearth closing in the bottom thereof andarotary head comprising a centrifugal oil and air projector dischargingoil and air draft over the hearth, alldesigned and operated to maintaincombustion adjacent the periphery of the hearth, I in combination with arefractory wall adjacent the peripheryof the hearth, said wall includinga face for impact of the discharged oil and upward deflection of thedraft, and another face which extends toward said fire box walls, and acooperating member affording supplemental refractory surfaces above andin reverberai'ory relation to the latter face of said impact wall andformed with spaced-apart passages for through flow of flame andcombustible mixture from the reverberatory space outward and upwardtoward said walls of the fire box.

17. Apparatus of the class described, including a flre box havingupright walls, a refractory hearth closing in the bottom thereof and arotary head comprising a centrifugal oil and air projector dischargingofl and air draft over the hearth, all designed and operated to maintaincombustion adjacent the periphery of the hearth, in combination with arefractory wall adjacent the periphery of the hearth, said wallincluding 7 a lower impact portion or element adapted to dewardlyinclined deflecting surfaces and formed and arrangedto'aifordspaced-apart paths for L rearward and upward escape of flameand combustible mixture toward said upright walls of said flre box.

18. Apparatus of the class described, including a flre box, a refractoryhearth structure including a hearth closing in the bottom thereof and arotary head comprising a centrifugal oil and air projector dischargingabove the hearth. said projector being of the high speed type and saidhearth having a substantially unobstructed upper surface lying below thelevel of normal projection of the discharged oil, said hearth structurehaving adjacent the periphery refractory elements presenting upwardlyand inwardly inclined surfaces and formed with passages for outward andupward through flow of flame and combustible mixture.

19. Apparatus of the class described, including a fire box havingupright walls, a hearth closing in the bottom thereof and a rotary headcomprising and air' draft over the hearth, all designed and operated tomaintain combustion adjacent the periphery of the hearth, in combinationwith a burner structure adjacent the periphery of the hearth, in thepath ofthe discharged oil and air draft, said structure includingspaced-apart surfaces in reverberatory proximity and formed and arrangedto afford paths for escape of flame and combustible mixture toward saidupright walls of said flre box. 4

20. A flame concentrator and director of the character described,including a grill having a flame-directing aperture, a deflecting wallextending upwardly toward said aperture, a deflecting surface in frontof said wall adapted to deflect an impinging draft upwardly intoa draftpassing above said deflecting surface toward said deflecting wall, and amixing valley intermediate said deflecting wall and deflecting surface.

21. A flame concentrator and director of the character described,including a grill .having a flame-directing aperture, a deflecting wallextending upwardly toward said aperture, a deflecting surface in frontof said'wall adapted to deflect an impinging draft upwardly into a draftpassing above said deflecting surface toward said deflecting wall, and avertical deflecting surface, extending transversely of said deflectingwall, intersurface in front of said wall adapted to deflect an.impinging draft upwardly into a draft passing above said deflectingsurface toward said deflecting wallpa mixing valley intermediate saiddeflecting wall and deflecting surface, and a vertical deflectingsurface, extending transversely of said deflecting wall, intermediatesaid wall and aperture. 23. In a flre box for oil burners of thecharacter described, in combination," a hearth, a grill support disposedon the hearth adjacent its periphery, and grill members adapted to bedisposed and supported in any selected places on the grill'support,whereby the spacing of the grill members from each other may be varied,said grill membershaving apertured portions disposed above the surfaceof the hearth when the grill members are disposed on the grill support.

24:. In a. flre box for oil burners of the character described incombination, a substantially annular hearth, and flame deflecting andcon-' centrating grill members disposed on the hearth adjacent itsperiphery, said'grill members having apertured portions incliningupwardly toward the center of the hearth and spaced vertical supportingwalls or flanges beneath said apertured portions directed approximatelyendwise toward the center of the hearth. 10

25. In a fire box for oil burners of the char acter described, incombination, a substantially annular hearth, flame deflecting andconcentrating grill members disposed on the hearth adjacent itsperiphery, said grill members having apertured portions incliningupwardly toward the center of the hearth and spaced flat verticalsupporting walls or flanges beneath said apertured portions directedapproximately endwise toward the center of the hearth, and anapproximately annular grill support disposed on the hearth, said grillmembers being supported thereon.

26. In a fire box for oil burners of the character described, incombination, a substantially annular hearth, flame deflecting andconcentratlng grill members disposed on the hearth adjacent supportcomprising supporting units having deflecting surfaces facing toward thecenter of the hearth and adapted to deflect an impinging draft upwardlyto andthrough the aperturesof said grill-members.

' 2'7. A fire box construction for oil burning fur-. naces of thosetypes which are provided with centrifugally-acting'distributing headsfor discharging fuel droplets substantially radially, including a hearthextending around and outwardly from said distributing head and includingan upstanding peripheral portion having an inner surface whichintersects the path of the discharged fuel droplets at substantiallyright angles, and an inwardly upwardly inclined portionoverhanging saidinner surface. 7

28. In a liquid fuel burning apparatus, in combination with a combustionchamber having a hearth and a wall to be heated and afuel impact memberset upon the hearth adjacent said wall, means for projecting fuel andair toward said impact member at relatively high velocity, ignitionmeans adjacent said impact member in the general path of fuel and airprojection whereby a combustion zone is formed adjacent said wall, and aperforated structuremounted above said impact member between theprojecting means and said wall, the perforations of said structure beingarranged in the general path of fuel and air projection and dischargingtoward said wall, whereby the flame in the combustion zone isconcentrated upon the wall in the vicinity of said perforated structure.

29. In a liquid fuel burning apparatus, in combination with a combustionchamber-having a hearth and a wall to be heated, means for projectingfuel toward said wall, means for supplying a blast of air at relativelyhigh velocity for admixture with said fuel to support combustionadjacent said wall, and means in the chamber for concentrating the heatof. combustion upon said wall, said means comprising a device consistingof a base structure and disposed adjacent the wall with one side formingan upright impact surface facing the air blast, said device consistingalso of a superstructure providing transverse passages or openingsthrough which fuel and air may pass toward the wall, whereby the flameof combustion is shorter than would be produced by the high velocity airblast in the absence of said device. I

30. A fire box construction for oil burning furnaces of those typeswhich are provided with centrifugally-acting distributing heads forflinging fuel droplets outwardly, including "a hearth extending aroundsaid distributing head and outwardly therefrom, and including anupstanding portion having an inner surface which intersects wall, meansfor causing air to intersect the fuel stream adjacent said wall, amember providing a fuel impingement and mixing wall having a surfacespaced inwardly from said "chamber wall in the direction of said fueldistributing means, and a flame-controlling structure overhanging saidimpingement surface and extending past the latter toward said uprightwall.

32. In a liquid fuel burning apparatus, in com-- bination with acombustion chamber having a. hearth structure including? a hearth and awall to be heated, means for projecting fuel and air toward said wall atrelatively high velocity, ignition means adjacent saidwall in thegeneral path of fuel and air projection whereby a combustion zone isformed adjacent said wall, said hearth structure further including meansprojecting upwardlyas a vertical continuation of the hearth and formi ga. fuel impingement surface adjacent said comb tion zone in spacedrelation to the said chamber wall, and means disposed between the upper'part of said impingement surface and said wall to spread and shortenthe flame produced in said combustion zone.

33. In a liquid fuel burning apparatus emboth'ing a combustion chamberhaving a hearth and a heat absorbing wall and also embodying means forpassing liquid fuel and air substantially horizontally through a portionof the combustion chamber at relatively high velocity over the hearth ofsaid chamber toward the heat absorbing wall of said chamber, meansforming an impingement surface spaced inwardly from said wall in thepath of the liquid fuel and air, means signed to reach high temperaturein operation,

means for throwing liquid fuel substantially horizontally toward saidimpingement surface to homogenize and gasify said fuel, means forsweeping air for combustion against said surface at high velocity tothoroughly carburet the homogenized fuel, means for igniting thecombustible facedesig'ned to reach high temperature in operapingementsurtion, said means being horizontally from said upright wall to formtherewith achamber,

horizontally toward said impingement surface to homogenize and easilythe fuel, means for sweepmeans for discharging liquid fuel substantiallying air for combustion toward said surface at high velocity tothoroughly carburet the homogenized fuel, means for igniting thecombined fuel and air, and'bailiing means disposed above saidimpingement surface and projecting into the upper part of thelast-mentioned chamber, said baming means constructed to direct part ofthe ignited mixture downwardly into said last-mentioned chamber.

FORREST A. HEATH.

